The general structure is for all the greenroofs the same. On the roofcover comes a root resistant membrane to protect the roofcover againt root penetration. Above this comes a protecting layer, drainage layer, filter fleece. The watercapacitie off the drainage depend on the kind of roof you want.
On the filter fleece comes the substrate where the plants will grow in. The substrate is composed of divers kinds of lava and special soil. The main goal is low weight but stil a good adhesiveness.